Walter Santos de Araújo

Ocorrência e caracterização de galhas entomógenas em uma área de floresta estacional semidecídua em Goiânia, Goiás, Brasil

In an area of seasonal semideciduous forest situated on Campus Samambaia of the Universidade Federal de Goias in Goiânia, Goias 34 types of insect galls were collected during the period 2005-2007. The galls occurred in 20 species of plants from 12 families, with Leguminosae (9), Styracaceae (6) and Ulmaceae (4) having the greatest number of gall morphotypes. Leaf and stem galls were the most widespread. Concerning gall morphology, the following were collected: globoid, discoidal, ellipsoidal, cylindrical and conical. The colour varied from green to yellow, brown and red. The galls were isolated or grouped and glabrous or pilose. The principal inducers were Cecidomyiidae (Diptera) and the parasitoids found were of the families Eulophidae, Torymidae, Pteromalidae, Encyrtidae (Hymenoptera). This is the first report of galls in four species of host plants for the Neotropical region.

Efeitos da sazonalidade e do tamanho da planta hospedeira na abundância de galhas de Cecidomyiidae (Diptera) em Piper arboreum (Piperaceae)

The objective of this work was to verify the effects of seasonality and the size of host plants on occurrence of Cecidomyiidae (Diptera) galls on Piper arboreum (Piperaceae). This study was carried out monthly, from September, 2006 to August, 2007, in a remnant area of Semidecidual Forest in Goiânia, Goias, Brazil. In each survey, 10 individuals of the host plant were chosen randomly, and the height, the total number of leaves, the number of leaves with galls and the number of galls per leaves were estimated. The abundance of galls varied significantly during the study period, being the greatest abundance found at the beginning of the rainy season. The height of the host plant and number of leaves per individual were also positively and significantly related to the abundance of galls, since larger plants offer greater availability of resources and sites of breeding. The results of this study suggest that the seasonality may be decisive in the abundance of galls as well as the architectural patterns of the host plant. The seasonal changes can directly influence the development of the host plant and thus alter the quantity and quality of nutrients offered to insects galling.

Edge effect benefits galling insects in the Brazilian Amazon

We investigated the influence of edge effects on communities of galling insects in the Brazilian Amazon. For this, were performed data analyses comparing the galling richness between disturbed and undisturbed areas, and subsequently evaluated the richness of galling at different distances from the forest edge. We registered 194 galling insect morphotypes in 116 host plant species. Galling insect richness was more pronounced in disturbed areas and closer to the forest edge, both to community in general as to specific host plant taxa. These results indicate positive responses of galling insect richness to edge effects in forest environments. Edge effect could influence the galling distribution in modified habitats because increases the stress conditions of the plants and decreases the attack pressure of natural enemies.

Can Host Plant Richness be Used as a Surrogate for Galling Insect Diversity

Galling insects are the only insects capable of manipulating plant tissues to form complex structures. The number of known species of galling insect is small compared to the large diversity that statistical estimates suggest for this group. The study of galling insect diversity can be a difficult task in mega-diverse environments such as in tropical regions, thus justifying the use of surrogates. This study investigated whether or not host plant richness and super-host taxa can be used as surrogates for galling insect diversity. Surveys were conducted in 15 areas of cerrado sensu stricto in different localities of the Brazilian Cerrado. The results showed that host plant richness was the main predictor of galling insect diversity. The plant genus Qualea (Vochysiaceae), with 18 galling species, was the super-host taxon used in the analyses. Despite the influence of genus on galling insect richness, the abundance of Qualea was not related to galling insect diversity. Surrogates can be a useful tool for estimating galling insect richness and diversity patterns, both of which are relevant for conservation assessments.

Contrasting effects of land use intensity and exotic host plants on the specialization of interactions in plant-herbivore networks.

Human land use tends to decrease the diversity of native plant species and facilitate the invasion and establishment of exotic ones. Such changes in land use and plant community composition usually have negative impacts on the assemblages of native herbivorous insects. Highly specialized herbivores are expected to be especially sensitive to land use intensification and the presence of exotic plant species because they are neither capable of consuming alternative plant species of the native flora nor exotic plant species. Therefore, higher levels of land use intensity might reduce the proportion of highly specialized herbivores, which ultimately would lead to changes in the specialization of interactions in plant-herbivore networks. This study investigates the community-wide effects of land use intensity on the degree of specialization of 72 plant-herbivore networks, including effects mediated by the increase in the proportion of exotic plant species. Contrary to our expectation, the net effect of land use intensity on network specialization was positive. However, this positive effect of land use intensity was partially canceled by an opposite effect of the proportion of exotic plant species on network specialization. When we analyzed networks composed exclusively of endophagous herbivores separately from those composed exclusively of exophagous herbivores, we found that only endophages showed a consistent change in network specialization at higher land use levels. Altogether, these results indicate that land use intensity is an important ecological driver of network specialization, by way of reducing the local host range of herbivore guilds with highly specialized feeding habits. However, because the effect of land use intensity is offset by an opposite effect owing to the proportion of exotic host species, the net effect of land use in a given herbivore assemblage will likely depend on the extent of the replacement of native host species with exotic ones.

Insect galls of the Parque Nacional das Emas (Mineiros, GO, Brazil)

In this study we perform an inventory of the insect leaf galls of the Parque Nacional das Emas, Goias State, Brazil. We found 97 gall morphotypes, distributed on 24 botanical families comprising 37 genera and 55 species. The plant taxa that showed the greatest richness of galls were the families Myrtaceae, with 17 morphotypes and Fabaceae with 14, and the genera Myrcia (Myrtaceae) and Qualea (Vochysiaceae) with 10 and eight morphotypes, respectively. The plant species Andira cujabensis Benth. (Fabaceae) and Myrcia guianensis (Aubl.) DC., with four morphotypes each, were the most diverse. We found galling insects belonging to Diptera, Hemiptera and Lepidoptera. The galling insects of family Cecidomyiidae (Diptera) were the most common inducing 38.1% of the gall morphotypes. All recorded gall morphotypes are first records to Parque Nacional das Emas. Among the 55 host plant species listed in the survey, 16 species (20%) have the first report of hosting galls.

Global effects of land use intensity on the impoverishment of insect herbivore assemblages

The modification of pristine wildlife habitats by land use is a worldwide cause of species extinction, as most native species cannot persist at high levels of human land use intensity. In this study, we gathered 90 lists of local interactions between herbivorous insects and their host plants to investigate the effects of land use intensity on the species richness and taxonomic diversity of insect herbivore assemblages. The effect of land use intensity on these insect herbivore assemblages was assessed using path analysis that controlled for differences in host plant richness, sampling effort, and the taxonomic range of plants and herbivores. We included the proportion of exotic host plant species in the path models to evaluate the extent to which the effect of land use intensity is mediated by the replacement of native with exotic host plants. Overall, we found negative effects of land use intensity on the species richness and taxonomic diversity of the insect herbivore assemblages, and these effects were mediated by an increase in the proportion of exotic host plant species. Since the effect of host plant richness was controlled for, our findings imply that the impoverishment of insect herbivore assemblages due to human land use is even greater than the loss of their host plant. A likely implication of such reduction in the species richness and taxonomic diversity of the insect herbivore assemblages is the accelerated loss of specialized plant-herbivore interactions, thus favoring interactions among generalist species and the biotic homogenization of species interactions across human-disturbed habitats.

Host plants of insect-induced galls in areas of cerrado in the state of Goiás, Brazil

Most studies of the interactions between plants and gall-inducing (galling) insects have focused on the entomological aspects, few having addressed the diversity of galls in relation to the characteristics of the host plants. The objective of this study was to analyze the richness and composition of the community of host plants of galls in areas of cerrado (savanna) in the state of Goias, Brazil. To that end, we inventoried the galls in different regions of the state and within various types of vegetation formations, between 2005 and 2007. We registered 80 gall morphotypes in 58 species of host plants (30 families and 47 genera). The host family with highest diversity of galls was Fabaceae, with 17 morphotypes, followed by Styracaceae, with seven. In the cerrado, Fabaceae is the plant family with the highest number of species. Our results show that the composition of a plant community is a determinant of the distribution of galling insects. At the family or genus level, the presence of certain taxa increases the species richness of the population of galling insects.

Uma nova espécie de Schizomyia (Diptera, Cecidomyiidae), indutora de galhas nos botões florais de Jacquemontia holosericea (Convolvulaceae)

Schizomyia santosi, a new species of Cecidomyiidae (Diptera), which induces flower bud galls on Jacquemontia holosericea (Convolvulaceae), is described as larva, pupa, and adult (male and female). Illustrations from the main morphological characters are given.

Checklist of host plants of insect galls in the state of Goiás in the Midwest Region of Brazil

Abstract Background Surveys of host plants of insect galls have been performed in different regions of Brazil. The knowledge of species of host plants of insect galls is fundamental to further studies of plant-galling insect interactions. However, a list of host plant species of gall-inducing insects has not yet been compiled for the flora of the Midwest Region of Brazil. New information We provide a compilation of the plant species reported to host insect galls in the Cerrado of the state of Goiás in the Midwest Region of Brazil. Altogether we found records for 181 species of 47 families of host plants, which hosted 365 distinct gall morphotypes.